Twitter is a young company generating large losses as it competes in a highly uncertain sector of the economy. And that is exactly why investors clamored for a piece of its initial public offering, which closed on Wednesday evening. Twitter’s shares were priced at $26, giving the company an overall value of $18.1 billion, including stock that the company is likely to issue to employees. That makes Twitter worth more than many storied American corporations, like Alcoa and Harley-Davidson. At that valuation, each of Twitter’s 230 million users around the world is worth $78. Going by such numbers, the public offering has been a tremendous success for the company, which raised $1.8 billion from the offering, a hefty war chest. All this is impressive for a company that has racked up more than $300 million of losses in the last three years — and may not show real profits until 2015. But investors are betting that Twitter is virtually destined to become wildly p...